792 THE GEOLOGY OF MINNESOTA. 



[ Kasalt. Amygdulefl. Quart zjt-e. 



No. 1824. BASALT. (ZirMyte.J 



Within the bay next east of Red Rock point, on the coast of lake Superior. 

 Ref. Annual Report, xxii, page 8. 



Meg. Shaly looking, thin bedded. 



Mir. The fine feldspars, which are somewhat altered, containing sericite scales, 

 lie in a matrix consisting largely of devitrified glass, which is darkened by fine 

 magnetite and by leucoxeiic, and contain, also, augite( ?) and calcite, with a little 

 quartz. One section. 



Age. Cabotian lava. N. H. w. 



No. 1825. BASALT. ( Zirkclyte with olivine. ) 



Same place as the last. 



Ref. Annual Report, xxii, page 8. 



Meg. The same rock as No. 1824, but having a spotted aspect. 



Mic. This differs from No. 1824 only in having fine olivine phenocrysts which, 

 however, are entirely altered to a fine, greenish substance, which is probably some 

 variety of antigorite. One section. 



Age. Cabotian. N. H. w. 



No. 1826. BASALT. (Amygdaloidal.) 



Phase of No. 1824; same place. 

 Ref. Annual Report, xxii, page 8. 



Meg. Rock like No. 1824, but containing numerous amygdules. These have a 

 bluish-green coating, and inside of this coating are at times several minerals and at 

 times only one. The common minerals are quartz, calcite, laumontite and thomsonite. 

 No section. 



Age. Cabotian. u. s. G. 



No. 1826A. AMYGDULES. 



From No. 1820. 



Ref. Annual Report, xxii, page 8. 



Meg. A collection of amygdules from No. 1826, most of them being of quartz. 

 No section. 



Age. Cabotian. u. s. G. 



No. 1827. QUARTZ YTE. ( Contact of gabbro. ) 



Southern face of mount Josephine, 500 feet above lake Superior. 

 Ref. Annual Report, xxii, page 8. 



Meg. Reddish, quartzitic. 



Mic. The most of the rock is qnurtz in large grains that interlock with each 

 other, though having in general a roundish outline. There is no trace of clastic 

 characters, but nearly every grain is thickly sprinkled with minute spicules, like 





